The terbinafine 250 mg oral tablet is prescribed for adults to treat a fungal infection of the fingernails and the toenails. It must be taken daily for six weeks to cure an infection in the fingernails, but taken every day for 12 weeks to treat a toenail infection. You must use it as prescribed, but there are possible side effects.
Terbinafine is an antifungal medication that destroys fungi because it interferes with a fungal enzyme called squalene epoxidase. Fungi use this enzyme to make a substance called ergosterol, a substance similar to cholesterol and a vital part of the cell membrane of the fungi. When terbinafine interferes with squalene epoxidase, the fungi cannot change squalene to squalene epoxide, the initial step towards making ergosterol, as explained in "Basic & Clinical Pharmacology" by Don Sheppard, M.D., Assistant Professor in the Departments of Medicine, Microbiology and Immunology at McGill University. Instead, squalene accumulates and ergosterol is not made.
According to the Mayo Clinic, you must be careful to follow the directions of your physician when taking terbinafine; otherwise, you will be more at risk for developing side effects. A small percentage have nausea and vomiting, diarrhea, abdominal pain, headaches and a strange taste in the mouth. There are other side effects that can develop, and if they do, you should immediately call your physician. These include severe nausea and vomiting, severe abdominal pains, vision changes, a significant amount of weight gain, a rash, yellowish eyes or skin, dark urine, fever, wheezing and swollen face or lips.
Yellow Eyes and Skin, Alcohol and Terbinafine
You can develop liver problems if you drink alcohol when taking terbinafine, so it is not advisable that you do so, per the Mayo Clinic. The alarming signs of yellowish eyes and yellowish skin can be signs of a problem with your liver. When the red blood cells break down, the hemoglobin in the blood cells changes to bilirubin and goes to the liver to be changed once more. If the liver is damaged, it may not be able to change the bilirubin and there will be too much bilirubin in the bloodstream, which can be seen in the yellowish eyes and skin.
Dark Urine, Alcohol and Terbinafine
Dark urine can be a sign of a liver disorder; if the liver is abnormal, the bilirubin may have to be excreted by the kidneys, which makes the urine have a dark color. If the liver was properly functioning, it would take the bilirubin and change it, then make it part of the bile, and release bile to the small intestines or send it to the gallbladder. Terbinafine is also metabolized in the liver, as explained in "Goodman & Gilman's The Pharmacological Basis of Therapeutics" by John Bennett, M.D., Chief at the National Institute of Allergy and Infectious Diseases. Thus, drinking wine when taking terbinafine puts you at risk for developing avoidable liver damage.